This is a grant proposal for continuation of work started two years ago under grant No. ES-01150 entitled: Carcinogenic Intermediates of Vinyl Chloride and Analogs. At the time the original proposal was submitted, we suggested that trichloroethylene (TCE) would be shown to be carcinogenic. Since then it has been shown by studies reported from the National Cancer Institute that this compound, TCE, is carcinogenic and the focus of our research has been on TCE. This renewal application is concerned with continued studies on the mode of action of TCE and related compounds. Biochemical, organic chemical and bioassay procedures are proposed in this application. The work suggested for this renewal application will further elucidate the mechanism of action of liver carcinogens and mode of action of chemical carcinogens.